Gallium nitride materials have enabled a diverse range of new device technologies spanning solid state lighting, short-wavelength lasers, and high-frequency/power electronics. It is one of many remarkable characteristics of GaN that light emitting diodes (LEDs) and high electron mobility transistors (HEMTs) can achieve excellent performance in spite of high defect densities, which are generally above 108 cm−2 on non-native substrates such as SiC, Si, and sapphire. Nonetheless, high material quality is clearly essential for devices such as blue laser diodes. New GaN device applications are emerging that will require low dislocation densities, including high-voltage p-n diodes and vertical junction field-effect transistors (VJFETs) for high-power switches as well as high-frequency III-N heterojunction bipolar transistors (HBTs). The performance of GaN LEDs and HEMTs can also be improved with the use of native GaN substrates.
Gallium nitride materials are difficult to wet etch using conventional wet etchants. Laser lift-off (LLO) is widely used to separate LED devices from sapphire substrates using a raster high-powered laser beam to vaporize the interface between GaN and sapphire. This process can, however, reduce yield due to cracking of the epitaxial material and is not presently compatible with native GaN substrates due to absorption of the laser wavelengths in the substrate.